This project will use measures of thought disorder to seek subvarieties of disorder within the broad and heterogeneous class of patients who are termed "schizophrenic." Seven cognitive tasks will be used, each of which consists of two subtasks. Aspects of thought disorder are measured by differential performance on the two subtasks of a task. These tasks seem promising for distinguishing varieties of schizophrenia. Using only drug-free patients, we will compare chronic schizorphrenics, newly admitted schizophrenics, nonpsychotic depressed patients, seniles, normal control subjects, and normal subjects in three schizomimetic conditions. We hypothesize that schizophrenics will show a bimodal distribution on score of differential error on six of our seven tasks, and that some of the error patterns measured by the differential error scores will be unique to a portion of the schizophrenics. We will also examine the relationship of error patterns to other aspects of the symptom picture, and will seek to identify meaningful syndromes within schizophrenia.